This invention relates to a technique for monitoring routes that have been advertised to other networks (ISPs) on the Internet.
The Internet comprises the largest known network of interconnected computers, each typically linked to others via a high-speed data link. While large entities such as corporations and universities may enjoy a direct link to the Internet, most individuals obtain access through an Internet Service Provider (ISP) such as ATandT Worldnet, for example. In the past, individuals have obtained such access through a dial-up telephone link. However, individuals can now obtain Internet access through via cable television networks and satellite links.
To facilitate a link between individuals connected to separate ISPs, at least one route must exist between the two ISPs. Moreover, an ISP intending to send data to another ISP must know of the existence of such a route. For that reason, ISPs will xe2x80x9cadvertisexe2x80x9d (i.e., communicate) such routing information to their peers to facilitate such connections. Most ISPs have implemented well-defined policies regarding which routes are advertised to their peers. Such policies attempt to ensure that packets inbound to an ISP from an external source take a predictable path across the Internet. However, ISPs have limited control over what their Internet peers (or other downstream peers) do with the advertised routes. For example, one ISP may readily modify an officially advertised route of another. Modifications of an ISP""s original advertised route can result in mis-routing of packets, including the complete loss or xe2x80x9cblack-holingxe2x80x9d of such packets. This problem is complicated by the large number of ISPs in existence today.
Most ISPs lack control over what they accept as an advertised route. For that reason, incorrect advertised routes from one Peer (ISP) can and do propagate to numerous other Internet Peers, effecting customers on all Peers that accept and use that advertised route. Presently, no industry-wide standards exist that govern modification of officially advertised routes. Further, there is no industry-wide pro-active method to notify an ISP if there is a violation of its routing policy by an external peer.
Thus, there is need for a technique for detecting violations of advertised routes.
Briefly, the present invention provides a technique for detecting and reporting routing violations in a network of interconnected peers, such as the Internet. In accordance with a preferred embodiment, routing information, including advertised routes, is received from each peer by a monitoring apparatus. In accordance with such routing information, the monitoring apparatus detects if a violation has occurred with respect to any advertised route. If so, the monitoring apparatus reports that violation so that appropriate action can be taken to correct the route violation, such as restoring a missing route, or updating the routing information maintained by the various peers to correct the modified routes.